Prepare a medium-hot fire in a charcoal grill with a cover, or preheat a gas grill to medium-high.

To make patties: In a large bowl mix together ground chuck, ground sirloin, 1-tablespoon lime juice, 2-teaspoons salt, black pepper, and corn. Handle mixture as little as possible to avoid compacting it. Divide the mixture into 6 equal portions and form the portions into patties slightly larger than the shape of the rolls. Do not press the patties tightly together. Cover patties and refrigerate for about 30-minutes.

To make spread: In a medium bowl stir together until well blended, cream cheese, green chiles, cumin and salt. In a small bowl put avocado and lime juice and stir together until avocado is coated with juice. Add avocado to cream cheese mixture and stir together until mixed. Cover and refrigerate until ready to assemble burgers.

Peel, thinly slice and separate into rings the onion. Cover tightly and refrigerate until ready to assemble burgers. When grill is ready and patties have chilled, brush the grill rack with olive oil. Remove the patties from refrigerator, uncover and place the patties on the rack, close grill cover, and cook, turning once, until done to preference, about 5 to 7-minutes on each side for medium. During the last few minutes of cooking, place the rolls, cut side down, on the sides of the grill rack to lightly toast.

To assemble burgers: On the split side of each roll bottom place an equal portion of the onion rings and add a patty to each. Top each patty with an equal portion of the green chili spread. Add the roll tops and serve. Makes 6 burgers.